[Issue 22981] Another forward reference bug involving a string mixin

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=22981

--- Comment #8 from Basile-z <b2.temp at gmx.com> ---
(In reply to Basile-z from comment #7)
> In `S` the non static member `E e` create a cycle but actually with a pass
> dedicated to "static members - only" , the internal enum `S.a` would not
> require `S` semantic to be complete.

reduced more

```
@(S.a)
struct S
{
    E e;
    enum a = "dfgdf";
}
```

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